Measuring Strength of VLS-grown Si Nanowires: AFM Bending vs. Nanoindentation

Abstract

Nanowires are known to have better electrical and mechanical properties than their bulk counterparts. However, widening of their applications is often hindered by the insufficient information of their mechanical properties. Although there have been many efforts to measure the mechanical properties of nanowires through various testing methods, the standard testing procedure has not been established yet and the results from each method show somewhat large deviation. In present work, we systematically performed both bending and nanoindentation experiments (which are two of the most popular nano-mechanical tests) on nanowires, in order to directly compare the result from each method. Used materials were Si nanowires, grown by vapor-liquid-solid (VLS) methods, with diameter from 30 to 100 nm and the tests were conducted with atomic force microscopy (AFM) and commercial nanoindentation equipment. From load-displacement data obtained from each test, elastic modulus and yield strength of the nanowires were estimated. The results were also analyzed in terms of the nanowire size effect on its mechanical properties. * This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government, MEST (No. R01-2008-000-20778-0).